Safety

This is the one absolute rule in this book. Safety must be your primary concern during a cruise. It must be the primary concern of everyone on the research vessel. There can be no bending of this rule. I have argued that sponsors may have millions of dollars riding on the success of a sea cruise. I have argued that your career may well depend on your success. These considerations are important, but they in no way compare with a human life. I am not an insurance underwriter and I do not think a price can be placed on a human life. When compared against any other consideration that you may face in working at sea, safety should always come first.

If those arguments don't sway you; if you are a bottom-line kind of person and believe that your data will change the course of history, that your data may be worth an injury if not a life, then think again. Any serious injury will lead to the immediate termination of the cruise. The ship will turn around and head for the nearest port. Your instruments may be left adrift at sea and your data opportunities will be lost.

In saying these things, I know that everyone reading this book will object, 'That's not me. I would never place myself or someone else at risk just to get some data.' Well once you start going to sea you'll find that you're faced with such decisions all of the time, and on some occasions you'll be sorely tempted to bend the rules. Even I'll admit that most of the time you can break the rules and get away with it. You must understand though that it is simply not worth the risk. When the temptation arises, you must resist and put safety first.

I recently had a conversation with a biologist friend who had been doing sampling work in a northern lake. He explained to me both the rules of diving and how he would stretch them, just a bit, to pull those last few samples from the frigid waters. He told me of one time when his diving partner had tired to the point that he couldn't go any further. My friend dove solo to retrieve the last sample. He shook his head about the incident and admitted it was dumb thing to do. He survived and there was no damage done, but the fact that this bright, intelligent scientist would put himself at risk for a single sample out of hundreds was striking. Much of our self worth gets tied up into our work. The importance of our work tends to become inflated in our own minds to the point that it can cloud our judgment. You must guard against this.

As a counterpoint, consider the speed limit on your local highways. In my area, the speed limit is 55 miles per hour (I apologize for the units). This is the maximum safe speed as determined by the authorities in my area. Does this mean I never exceed 55 mph? Hell no. (In case my insurance company reads this I won't tell you how fast I do drive.) After all, under good conditions virtually all of the roads I travel can easily support speeds higher than 55 mph. While I know that statistically the accident rate increases at speeds above 55 mph, I trade off some margin of safety versus the extra time I save by traveling at a higher speed.

Many decisions that you face on board ship will be like the one we each face when deciding how fast to drive. For example, you may have to decide whether to wake someone who over slept or just bring a buoy onboard with one less person handling lines on deck. In calm seas the decision is easy. As the seas build your margins of safety are reduced. Where do you draw the line?

In each instance you'll have to make the decision individually. My argument is that if you do err, err on the side of safety. Take more care than you would on land. Be aware of the alertness and mental condition of each person in the crew. When things go smoothly, deployments and recoveries are easy, and even a little boring. Boring is good. Accidents typically occur due to a chain of events and you want to be sure that everyone is certain of their responsibilities and alert to problems as they occur.

Another aspect of safety that you need be aware of is that not everyone thinks of safety in the same way. I was at a Navy port one time preparing for an experiment when some investigators from another institution launched a small research catamaran of less than 5 m length into the water for the first time. They had mounted a guard's shack on top of this catamaran and filled it with instrumentation racks. When the vessel was lowered into the water it nearly sank to the top of the pontoons. With a scientist on it, the hull would actually partially submerge. When I, playing the part of Richard Dreyfuss in the movie Jaws, suggested that the vessel was a bit overloaded, I was told that it would be fine. After all they were only going a few miles off shore!

These investigators had no concept of boat safety and were going to unknowingly risk their lives to gather data. After being blown off by the investigators I did not hesitate in raising my concerns with the APL test director and the Navy's test liaison and safety officers. After a brief inspection, much of the equipment and two scientists were removed from the vessel (and here I use the term loosely) and an experienced pilot was added to the crew list. In the end, these investigators ended up getting their precious data but at a significantly reduced risk to life and limb.

To me the surprising thing about this story, is that these investigators, who I think were being so dumb about safety, are very smart guys. I respect them as researchers, but intelligence and skill in research do not assure common sense when it comes to safety. We all have our blind spots.

Training

The keys to avoiding accidents are training and awareness. People need to be trained in the do's and don'ts of all manner of ship activities. At the same time, they need to be vigilant and aware of conditions around them. I liken this requisite awareness to the capability of a football quarterback to see the entire field. By this, I mean his ability to perceive and quickly evaluate the total picture of what is going on about him.

Let me be specific. I once hired a technician to work on what was his first and last cruise. We carefully reviewed safety procedures and it was clear he understood that he should never walk under an object lifted above the deck. Still, several times during the on load he would simply stand under a load while it was swung over him. I pointed out his error and he promised to be more careful. On our second day at sea, we began deployment operations. I was in the lab when one of our engineers came in to complain about our new technician. I walked out onto the deck to see him standing obliviously under a 100 kg buoy suspended 3 m off the deck. After I removed him from the deck, I threw a minor fit. I asked him what he had been doing. He said that he just wanted to help out if he could. He wasn't even aware of the buoy that was suspended over his head. He explained to me though that he was confident that the lifting strap and bridle would hold - he couldn't see why I was upset. At this point I had calmed down enough to quietly explain to him that he was banned from the deck of the ship during all deck operations. He thought this was unjust, but I explained the reasons for the rules, I explained that I expected everyone in our party to follow those rules, and I explained that his indifference to those rules had placed both his safety and the expedition in jeopardy.

I am not certain awareness can be taught. Everyone knows that you are not to stand in the bite of a line, but this is quite different than recognizing, while working to deploy a buoy on a heaving deck, that you are standing in the bite of a line. (A bite is an open loop of line. If you step into the loop, and the line goes taught, it can tighten around your foot or leg so that you cannot get loose.) Menard put it in this way:

...A more common problem is that inexperienced scientists have unjustified faith in the reliability of winches and other ship equipment. Consequently they do not take steps to avoid improbable misadventures and accidents. The experienced oceanographer takes precautions to avoid any conceivable equipment misbehavior and expects that highly improbable events will surely occur. One time the power lead to the main dredging winch on one of our ships was being repaired in the engine room. No one was near the winch, and a colleague and I were leaning against the after rail awaiting developments. We were directly on a line between the dredge on the deck and the sheave on the end of a boom through which the dredging wire led to the winch. I remarked "Max, no one is near that winch, and I don't see how it can start. However, if it does, the dredge will be pulled across the deck, pin us against the rail, tear it away, knock us over the side, get jammed against the sheave, break the cable, and fall on top of us in the water. It seems to me that the view is just as good six feet over there where we are not on a line with the winch." We idly moved over, exchanging sea stories. A moment later, the winch started to haul in even though no one was near it. The dredge moved across the deck, tore away the railing, jammed in the sheave, the wire broke, and the dredge disappeared into the deep. We stared at these nearby and dramatic events with some amazement. Shortly, the winch operator climbed out of a hatch leading up from the engine room and after stopping the winch explained that he had shorted some wires down below.

One thing that I do before each and every cruise is to have the members of my party read and review a copy of the APL safety manual. While the people who have been to sea with me before always groan at having to reread this manual for the N-th time, I think a safety review prior to each cruise is a big plus. I reread the safety manual myself before each cruise because I find its advice useful.

I am sure that other organizations have their own safety manuals. While the APL safety manual, which is excerpted in Appendix A, is not meant to be a complete guide to at-sea safety, it does provide a number of useful guidelines. I have included excerpts from the manual here in the hopes that you will read it and use it prior to your cruises. These are not arbitrary rules, but are based on years of experience by people at APL and elsewhere. The author of the APL safety manual drew heavily upon standard references in the field. Not all of it will apply to any given operation, but read it all none-the-less. You never know when following these rules might save someone's life.

The other thing that I do just prior to each cruise is to have a safety meeting with all of my personnel. I make it clear that my number one priority is to have a safe cruise and that safety supersedes all other concerns. We review the most important safety rules and discuss any questionable activities that we anticipate during the cruise, including all deck or small boat operations. I finish by emphasizing that safety has to be everyone's concern. I don't want anyone doing anything that they feel uncomfortable with and I explain that there will be no negative repercussions for voicing safety concerns during the cruise.

Deck Operations

Deck operations include all aspects of lifting and moving objects on the deck of a ship. Deck operations typically include the use of cranes, A-frames and winches to lift objects onto the ship during on load, into and out of the water during deployment and recovery operations, and off the ship during offload. Deck operations, and deployment and recovery operations in particular, are the most dangerous activities on ship. All participating personnel should be trained in the proper procedures for the safe deck operations.

The dangers from deck operations are several fold. First, cranes, lifting straps, and bridles have been known to break releasing their load to the deck. I have seen it happen and it is a terrifying site. A few hundred kilogram buoy falling from a meter height can do a lot of damage. Second, anytime you lift an object off of the deck of a rolling ship, that object will swing about. Tag lines are used to control the swinging of suspended objects, but a large swinging buoy can be dangerous to the crew and itself. Finally, most deployment or recovery operations involve personnel working near the edge of the deck. With the confusion of the moment, the clutter of a typical deck, and large swinging load, it is all too easy to lose someone overboard.

These dangers are reduced by limiting personnel involved in deck operations, establishing a clear chain of command for the operation with a single person in charge, planning all aspects of the operation, use of the proper equipment, and individual attention to safety.

Almost as an aside, Herman Wouk, who served in the Navy during World War II, wrote these paragraphs that well describe the confusion of deck operations in his famous novel, The Caine Mutiny:

"At four o'clock the minesweepers formed a slanting line, a thousand yards apart, and began to launch their sweep gear. Willie went to the fantail to watch. He could make no sense of the activity. The equipment was a foul tangle of greasy cables, shackles, floats, lines, and chains. Half a dozen deck hands stripped to the waist swarmed about under the eye of Maryk, uttering hoarse cries and warnings larded with horrible obscenities as they wrestled the junk here and there on the heaving fantail. Waves broke over their ankles when the ship rolled, and water sloshed around the gear. To Willie's eye it was a scene of confusion and panic. He surmised that the Caine crew were unfitted for their jobs, and were fulfilling the ancient adage: When in danger or in doubt, run in circles, scream and shout. "

Despite the fact that later in the novel, Willie reevaluated his opinion of the efficiency of the crew in performing deck operations, I still find the description a vivid and apt one.

Rules of Deck Operations

The first rule of deck operations is that only those that are directly involved with the operation should be on the deck. All other personnel not directly involved with the operation should be well clear of the area. There are several reasons for this rule. First, it minimizes the number of potential victims, should something go wrong. Second, it maximizes the amount of free space available to those working on the deck to get clear of a falling or shifting load. Finally, it reduces the possibility of confusion.

Unfortunately these simple rules are not always followed. I was once involved in a search and recovery operation on a research vessel. The ship had lost an expensive CTD system in about 80 m of water and we were attempting to locate and recover the instrument. Everyone on board was anxious to help, and so when we began our search operation, everyone on board, including the cooks, were at the midship starboard station trying to help. The confusion and chaos was so overwhelming that I ordered the retrieval of the acoustic sensors we were using for the search and marched up to the bridge (at least the Captain was on duty) to ask for some order. After strict orders came down from the bridge that no one was allowed in the working area without direct orders from the Captain or the ship's Chief Engineer, order was restored and the search continued. It is amazing how much confusion can be sown by otherwise well-intentioned people.

Confusion in deck operations is also minimized by establishing a strict chain of command before the deck operation commences. There must only be one person in command of the operation at any one time. I'll refer to this person as the scientific deck officer. On APL cruises the scientific deck officer is normally not a scientist, but one of our senior technicians with the most at-sea experience. We have found that the scientists typically do not have the experience necessary to deal with all possible problems that might arise and that scientist's judgments regarding safety issues are often clouded by their interests in the outcome of the operation.

Usually the scientific deck officer will have little else to do other than direct the others on the deck. This is because it is surprisingly difficult to direct others when you are wrestling with a 500 kg buoy on the end of a tag line. The scientific deck officer also usually has to have both hands free to give hand signals to the crane operator. The APL safety manual calls for a separate safety officer whose sole job is to monitor the safety of the operation. We usually give the scientific deck officer that safety role, which further restricts their physical participation in the operation. A final reason to keep the scientific deck officer free of physical responsibility is that if something does go wrong then they can either summon help or freely act to correct the situation.

While it is rare, it will sometimes be necessary for command to switch from one person to another during a deck operation. For example, when deploying a buoy, the scientific deck officer might have control of the operation while the buoy is over the deck, but that control may switch to the crane operator when the buoy is over water, well away from the ship. This might occur in situations where the crane operator would be in the best position to determine exactly when to lower the buoy into the water to minimize the possibility of damage. Such switches in responsibility need to be carefully planned and understood prior to commencing any operation.

This leads to our next rule of deck operations - every operation should be planned prior to commencement. All personnel should then be briefed on the overall operation and exactly what role they are to play in the operation. This sounds so military that it brings to mind the preflight briefings that you see in all those old war movies before the pilots go off on a bombing mission. While I don't mean to imply anything quite so formal, the idea is actually the same. It is important in these operations that everyone is working together, understands their responsibilities and what to do in case of an emergency. In particular, we always discuss exactly what each person will do if the buoy gets loose on the deck (which is always more frightening for spherical buoys!) We then synchronize watches and off we go.

In addition to training and planning, it is important that all deck personnel have the proper equipment. On UNOLS vessels, as well as vessels used by APL, hard hats, gloves, and personal flotation vests are mandatory. People regularly complain about this requirement, but it is important. The biggest single complaint regarding the required equipment is usually about the restriction of movement from wearing a personal flotation device. Despite these complaints, modern personal flotation vests are quite compact and do not present any significant hindrance to movement. On the other hand, the cheap lifejackets that are available for scientific personnel on some ships are atrocious in this regard. My solution is to take my own personal work vest on each and every trip. This way, if the ship has old bulky vests, I can work safely and still be comfortable. There is also a great advantage in having your own vest in that others won't be readjusting the straps all the time.

I also take along my own hard hat, although I have never been on a ship that didn't have them. It does add a bit of professionalism though to your operation when you show up with your own safety gear. And again, I don't have to worry about adjusting the hat each time I go to put it on. One piece of advice though on the hard hats - don't lean over the side while you are wearing one. I was on one cruise when the scientists lost five of the ship's hard hats by looking over the sides at the end of buoy deployments. I don't think the skipper was too happy about the prospect of explaining his losses to the marine department on his return!

These rules about organization and equipment are important, but the most important rule is a simple one: keep you eyes on the load. When a load is lifted above deck, you should always be aware of its location, attitude and velocity. People who don't keep track of the load should not be on deck.

I was on a cruise once with a scientist who was directing the deployment of a small buoy with the help of a crane operator from the crew. Once the buoy had been lifted over the side, the scientist noted something about the buoy that was not quite right. He motioned for the crane operator to stop the deployment. The scientist then dropped his tag line, turned his back to the buoy, and walked away to get a tool. While the day was calm, the ship had some roll to it, and as I watched, the buoy began to swing. It finally collided with the side of the ship with a resounding thud. The scientist ran back to the tag line, got control of the buoy and directed the crane operator to recover it. While the damage was minimal, the scientist started to chew out the crane operator for letting the buoy bang up against the side of the ship. At this point I stepped in to point out that the crane operator had done exactly what he had been told to do, and that the scientist was at fault for letting go of his tag line and walking away. The moral of the story is to always think about what is going on during deck operations. A second moral is to not blame others, especially the crew, for your own mistakes. This I'll discuss in more detail in the chapter on People.

Night and Heavy Seas Operations

As scary as I make things sound, daytime deck operations in calm weather are surprisingly mundane. From the viewpoint of safety, a boring cruise is a good cruise. Night time and/or heavy seas operations are a different story. When operating at night, all personnel should also carry personal safety lights on their work vests. Without a light at night, a person is almost impossible to find. Also more attention has to be paid to deck obstructions that are harder to see at night. Personnel checks should be completed before and after each operation to insure that no one was lost during an operation. I know this sounds silly, but before leaving the deck each individual in the deck crew should notify the scientific deck officer. We have yet to lose anyone on a cruise I was involved in, but on more than one occasion we have had to search the ship for personnel when they have wandered back to bed after a nighttime recovery without telling anyone.

Heavy seas operations are another matter altogether. Before any heavy seas operations are begun, the scientific deck officer needs to determine if the operation can be done safely. We usually avoid trying new types of deployments or recoveries during heavy seas because of the increased risk of accident. Typically, when a smaller vessel is running in heavy seas, safety lines will have to be rigged and used. Safety lines run along the deck from one tie point to another. The deck crew wear harnesses with lines of a few meters in length that can be attached to the safety lines. The attachment is usually through a clip of some sort that will hold the line to the safety line, but will allow the clip to slide back and forth so the crew member can move along the deck, up and down the safety line. It is critical in these operations that you are attached to a safety line at all times. If you need to move from one line to another, unclip from one and clip back onto the other line immediately. The lines will do you no good if you are not attached to them. The second critical point is to remember at all times that you are on a safety line that could restrict your freedom of movement in case of an emergency. Thus keep your line clear of other lines at all times, keep it away from deck obstructions (cleats, protruding plates and the like), and keep an emergency retreat path in mind should something go wrong.

In any case, where you need to go out on deck at night or in heavy seas, it is a good idea to use the buddy system. That is you find someone to go outside with you to keep a watch on you while you are working. In this way, if you fall overboard, there will at least be someone there to notify the rest of the crew of your predicament.

Tag Lines and the Control of Loads

If you are working on a deck operation, odds are you will be holding a tag line to control the motion of a buoy. Tag lines are amazingly simple devices (you can't get much simpler than a piece of rope), but I cannot tell you how many times I have seen scientists apparently mystified by how to work a tag line. So here is the number one rule of tag line operation: tag lines don't work if you push on them, tag lines only work if you pull! In fact the whole idea is to maintain tension on the line at all times, using the opposition of forces to control the object. With multiple tag lines used on heavy objects, the lines should be spread about the object so that the opposing tension comes from pulling against your fellow crew. On lighter or longer objects with more of a moment arm, the opposition can come from pulling on the pendulum formed by the object and its support.

Let me say it again, tag lines don't work unless you pull on them. Never let them go slack. The idea is to damp out the motions through the use of opposing force. On a calm day, invariably scientists will let their tag lines go slack because the load is not moving much. A few moments later, when the load gets to swinging from the gentle sway of the ship, they panic and have to pull with all their might to try to steady the beast. This is nuts. A little bit of tension applied at the proper times can go a long way to insure that the swaying never begins. Remember that momentum is mass times velocity. If the velocity is kept small then the momentum will be small.

Another critical point is to never work a tag line that is too short. At the maximum lift of the crane (which is the most dangerous point in terms of the object being dropped) you should be well away from the object. If the tag line is so short that you end up standing under the object then a) you are not doing much good in restricting the motion of the buoy anyway, and b) if the buoy falls your spouse will be able to live it up on the insurance money.

Another mistake I see nearly every newcomer make is to wrap the tag line around your hand to get a better grip. I did this myself when I first went to sea. It seems to be a natural instinct. My advice here is simple: don't. When an object is lifted in the air, you must be ready for it to fall at any given moment. If a buoy fell into the sea with a tag line wrapped around your hand, you could end up doing significant damage to the railing of the ship as you are dragged through it and overboard. This would really upset the skipper as he'd probably have to fill out a million forms explaining your dismemberment when he got back to shore. It's not good to upset the skipper, so don't wrap the line about your hand.

Finally, on our list of do's and don'ts for use of tag lines, watch the tangle of line that will inevitably end up behind you. While your primary attention must be on the load, if the crane support failed, the line behind you could take you with it as it raced to follow the buoy. To sum it all up: be careful and aware, keep you lines taut, and act as if the crane will fail at any moment.

The Most Dangerous Times

There are two points of maximum danger during deck operations. Danger to personnel is maximum when the load is suspended over the deck, while danger to the instrument is maximum when it is suspended over, but not in, the water near the side of the vessel. These are important points to keep in mind for safety and success in deployments and recoveries.

A swinging load above a deck cluttered with people and obstacles can cause quite a bit of damage. The key is to keep things well controlled as I have described in the previous sections. If a load does manage to get away from you over the deck, then the solution is to set the load down onto the deck (but by all means, do not release it) to control its motion. This may break some instruments but it can prevent injury. I have seen smart crane operators do exactly this when the scientists let a load get away from them.

The funny thing is that the most dangerous time for people is not the same as the most dangerous time for the buoy. When a buoy is swinging above a deck, it usually won't be in a position to hit anything other than a scientist or two, and a person colliding with an oceanographic buoy at a few meters per second does very little damage to the buoy. The most dangerous time from the buoy's viewpoint is when it is hanging over the side of the ship, but is not yet in the water. Typical ship's cranes do not have that much reach and thus a buoy can bang up against the side of a vessel if it gets swaying when it is over the side. Once in the water, of course, the water itself will dampen the motions of the buoy sufficiently where it is not a danger. The point here is to deploy and recover buoys as far away from the ship as possible AND to minimize the time that the buoy is out of the water and next to the ship hull.

On deployment, once the buoy is swung over the side, it should be lowered into the water as soon as possible. If you notice something wrong with the buoy after it has been lifted, it is usually best to put it back into its cradle to fix the problem. Don't try to work on a buoy suspended over the side. It is a sure way to loose tools and instruments. (Believe me I have tried, and lost both. I have littered the ocean floor at a variety of test sites over the years with wrenches, screwdrivers and wire cutters. If you ever happen to come across a tool on the bottom when you are diving in the DSV Alvin, then it is likely mine.) On recovery, once the buoy is hooked, it should be lifted above the ship as soon as possible. This also minimizes the length of the pendulum and hence the buoy motions.

There is yet one more danger point to both people and buoy while the buoy is "safely" in its cradle. While it is not as severe a problem as during deployment, be aware of the damage that can be caused if someone accidentally walks into the buoy and bends or breaks a protruding sensor, connector or antenna. The best way to prevent this problem is to make the support cradle large enough to prevent people from walking too near the buoy.

Ship's Crew

I'll complete this section by briefly mentioning the ship's crew. I have averaged just one sea cruise a year over the past several years. With an average duration of 10 days, that means that it takes me ten years to gain about one hundred days of at-sea experience. Most of the crew members that you will sail with gain this same experience in a single year. Most crew on scientific research vessels know more about the handling, deployment and recovery of oceanographic equipment than you or I will ever know. Listen to them. Seek out their advice. Give them a stake in your work by explaining to them what you are doing, by including them in your operational planning, and by listening to their input and suggestions. You may know more oceanography than they do, but they know more about working at sea. Only a fool would not avail themselves of such expertise.

Electrical Safety

Up to this point I have talked about mechanical safety, but there are other dangers for oceanographers at sea. Electricity and sea water don't mix. (I think I once read this in a chemistry textbook.) Instruments today are getting smaller and run on less power, so that many operate from low voltages. Still dangers abound for the unwary or untrained.

For example, many CTDs and samplers utilize a 48-volt power supply for their operation. This 48-volt power is conducted to the instrument via a single wire with a sea water return completing the circuit. This works fine when the instrument is in the water, but when it is brought out of the water the 48-volt potential appears directly on the instrument case or electrode. This can be lethal. A good safety precaution is to connect a grounding strap to the instrument before handling it onto the deck. Unfortunately, this is one of those rules that is constantly violated within the physical oceanography community. Similar dangers occur with autonomous underwater vehicles, although I understand that many people within this community take the danger more seriously, and regularly use grounding wires.

I have been involved with the fabrication or repair of electronic devices out on deck during the outbound cruise to a test area more times then I care to admit. When using power tools on the deck of a ship, you should take precautions. Don't work with power tools in areas subjected to splash or spray. Always use grounded receptacles and grounded extension cords. And avoid standing water on the deck.

Another potential source of danger arises on ship due to the differences between ship's power and the standard power that we get back on land, at least for U.S. citizens. Within the U.S., the standard 120-volt AC plug has three prongs: two flat prongs for the AC current and one round prong for the ground. It turns out that one of those AC prongs is also grounded back at the main junction box, so only one prong should have a nonzero potential relative to ground. (If you look at a two-prong AC plug in the U. S., you'll likely find that one of the AC prongs is a little bigger than the other. This difference enforces the polarity of the connection so that, for example, the chassis of TV will be at ground potential.) The U. S. system differs from European power where both AC prongs, on a three-prong plug, have 110-volt (rms) potential with respect to ground. The potentials on these two AC prongs are out of phase, so that the potential between them is 220 volts.

Ship's power is almost always like the European system in that neither of the two AC prongs are grounded. This should make no difference for transformer isolated equipment, but it can become a hazard for equipment which is not transformer isolated. Such non-isolated equipment is required by electrical safety codes to be designed so that no portion of the chassis is accessible from outside of the case, and all exposed metal must be insulated from the AC ground. Still, insulation can break down. Furthermore, when such a piece of equipment fails, you may be tempted to open it up to work on it. Be forewarned that this can be more dangerous on board a ship than back in your lab. If you are forced to work on a piece of non-isolated equipment, you should use an isolation transformer and check the chassis potential with respect to the hull prior to touching anything.

A few years ago I was on Flip when a colleague experienced dangerous problems with a non-isolated piece of equipment. My colleague was setting up the equipment to support a simple acoustic experiment. Acoustic transducers had been mounted on Flip's hull prior to deployment. The setup used a pulse generator driving a high power audio amplifier which in turn drove the transmit transducers. Separate receive transducers were connected through a preamp to a data acquisition system. Since he was dealing with a high power system, and the transducers were underwater and unreachable, my colleague hooked his equipment up cautiously. He checked to insure there was no short between the transducers and ground. He connected the transducers to the amplifier and powered it up without any signal. He then checked the voltage levels on the transducers and all seemed OK. He finally turned everything off and hooked up the pulse generator to the input of the power amplifier. I walked into the lab just as he turned the switch on. Immediately the system began smoking, not a pleasant sight (or smell) on board a ship. Quickly the power amp was shut down. My colleague almost burned himself when he attempted to remove the coaxial cable between the power amp and the pulse generator. It was red hot and in fact was the component that had started smoking.

After some analysis and schematic reading it became apparent that the design of the power amp was at fault. The amplifier power supply was not transformer coupled, but instead ran directly off the AC line. When AC power was applied to the power amp, the input "ground" went to a potential of 60 volts above Flip's hull and the output ground of the pulse generator. All of the ground connections were nice thick pieces of wire so who knows how many amps of current were forced through the outer braid of that RG-58 coax before the power was removed. To make matters worse, an inspection of the power amp indicated that it had been modified, which had the effect of making the entire chassis electrically hot. While this amplifier was marginally safe back in the lab, it could have easily electrocuted someone on board ship.

In the end, Tim Stanton of the Naval Postgraduate School came to the rescue to salvage the acoustics experiment. He replaced the deadly power supply in the power amp with a much smaller, but isolated, laboratory supply that someone else had brought on board as a spare. It turned out that the experiment was using very short pulses and a low duty cycle so the replacement power supply did not have to provide a tremendous amount of power.

The moral of this story is that you should know your equipment and understand how it will operate on the peculiar power distribution systems available on board ships. A lack of understanding can be dangerous.

Finally, I'll make a comment about power transformers. I have had the opportunity to participate in a number of cruises on foreign research vessels. The AC on foreign ships is invariably 220 volts at 50 Hz. It is fortunate that more and more U. S. built equipment is capable of directly handling 220-volt power, either automatically or by throwing a switch. Still, there is some U. S. equipment that requires 110 volts. In these cases I always take along some 2:1 step-down transformers to convert the 220-volt power to 110-volt power. The point that I want to make is that when faced with these circumstances you should avoid using autotransformers, but instead should use full isolating step-down transformers.

The prototypical isolating transformer has two windings about an iron core. The primary winding, which is connected to the input, is electrically isolated from the secondary winding, which is connected to the output. Thus one side of the output can be grounded without grounding the input. An autotransformer only has a single winding, but with a center tap. In the case of a 2:1 step down autotransformer, the input voltage is applied to the two ends of the winding and the output is taken from between the center tap and one end of the winding. Thus the input is not isolated from the output and grounding one side of the output may act to ground one side of input. Autotransformers are popular for voltage conversion because they are cheaper to make and weigh less than a full two-winding transformer. Despite these advantages, autotransformers should not be used on board ships, because grounding one side of the power distribution system on a ship is not advised.

While ideally you should use transformers designed to operate off of 50 Hz, these are usually hard to find and therefore expensive. While I am not recommending this to others, I have found that good quality 60 Hz transformers can be used at 50 Hz as long as they are operated well below their maximum rated current specification.

Laser Safety

Another major personal concern of mine is laser safety. Working in the field of ocean remote sensing, there are numerous systems that use lasers. I have been involved in two separate programs where investigators with laser-based systems assured everyone that the systems were eye-safe, only to find out later that they were not. One investigator claimed that his system was eye-safe because of the statistical rarity of the nadir- pointed beam actually reflecting off of the ocean surface and hitting someone in the eye. Our laser safety officer at APL told me that while statistically this might be a rare occurrence, it would take only a single short pulse from this system reflected from the surface into your eye to do serious damage; damage that would likely not be felt until years later. This scared the hell out of me. Needless to say this system was not allowed to operate during our experiment.

In the second case, a scientist from a small company convinced one of our sponsors to support their measurement of surface currents from shore by laser ranging to some cheap plastic buoys deployed in the near-shore environment of the coast of California. I personally did the laser safety calculations, and then had them double-checked by our laser safety officer. The calculations showed an eye-safe range of 200 m, which was deemed adequate for our operations. Just before the test was to begin, the laser safety officer from the Navy base where we were operating, came to see me. After introducing himself he began to chew me out about our unsafe laser operations and the inadequacy of our test plan. I objected that I had written the plan and done the calculations. I explained that the laser eye-safe range was 200 m and that no one would be within 1 km of the laser. The laser safety officer was unimpressed. He had just returned from the laser site where he had measured the laser power directly. His calculations indicated that the eye-safe range was 2 km! It turned out that the laser scientists had discovered that they needed more power to see their targets, so they just opened up their optics to increase their power. They weren't going to tell anyone about it because they were afraid we would shut them down. It is amazing to me that normally sane people would risk someone else's eyesight for a bit of data. I ended up throwing a fit that was heard back in Washington, D. C.

Hopefully after my little laser-safety diatribe you'll be forewarned. We use low power lasers for a lot of things and they are incredibly useful and safe. I just have problems with the higher-power, short-pulse variety. I also find it amazing that while I can't buy or store explosives legally, anyone with money can buy a laser that can seriously damage eyesight. I once saw a 2 W laser waved about a room by a high school student at a science fair I was judging. After I confiscated the system from him for everyone's protection, he explained that his rich uncle had bought it for him. Simply amazing.

Radar Safety

I happen to do a lot of work with radar remote sensing in my career, so radar safety is another topic of importance to me. Being in the field has led me to realize that everyone should take heed of shipborne radars. Every ship has at least one navigation radar and you need to be aware of the dangers of strong electromagnetic fields.

The effect of low level electromagnetic radiation on humans is a topic of some controversy. I am not qualified to get into that debate. There is no debate though about the dangers of human exposure to high-level electromagnetic fields. Modern ship navigation radars create such fields within a few meters of their antennas. These radars are usually mounted on the mast above the bridge, and their antennas are extremely directional. So it is usually safe to stand beneath the antenna. Just be certain that all radars are turned off if you go aloft to mount sensors. The electric fields near the communications antennas can also be quite intense, so unless the transmitters are quiet, stay away from them as well. You usually have to notify the officer on duty when you are climbing above the bridge anyway, so just try to be safe.

Safety Checklist

• Force everyone in your party to re-read your institution's safety manual, Appendix A of this book, or some other appropriate safety manual
• Conduct safety meeting just prior to cruise
• Keep aware at all times while on board
• Continue to perform safety training on board
• Anticipate equipment failures and make contingency plans to keep everyone safe
• Keep loads low to the deck wherever possible
• Make proper use of tag lines, and never wrap a line around your hand
• Keep deck crew to a minimum
• Use proper safety equipment
• Don't go out on deck alone at night or in heavy weather
• Never stand under a load
• Be aware of the dangers of ship power
• Be extra careful of lasers and radars